LIBRARY

STANDARDS

Interfaces documented on this reference page conform to industry standards
as follows:

get_wch,
wget_wch,
mvget_wch,
mvwget_wch,
unget_wch: XPG4-UNIX

Refer to the
standards(5)
reference page for more information
about industry standards and associated tags.

DESCRIPTION

The
get_wch,
wget_wch,
mvget_wch, and
mvwget_wch
functions read a character
from the terminal associated with the current or specified window. In no-delay
mode, if no input is waiting, these functions return
ERR.
In delay mode, the program waits until the system passes text through to the
program. Depending on the setting of
cbreak, the program
waits until it receives one character (in
cbreak
mode)
or the first newline (in
nocbreak
mode). In half-delay
mode, the program waits until the user types a character or the specified
timeout interval has elapsed. Unless
noecho
has been set,
these routines echo the character into the designated window.

If the window is not a pad and has been moved or modified since the
last call to
wrefresh,
wrefresh
is called
before another character is read.

If
keypad
is enabled, these functions respond to
the pressing of a function key by setting the object pointed to by
wch
to the corresponding
KEY_
value defined
in
<curses.h>
and returning
KEY_CODE_YES. If a character (such as escape) that could be the
beginning of a function key is received, Curses sets a timer. If the remainder
of the sequence does arrive within the designated time, Curses passes through
the character; otherwise, Curses returns the function key value. For this
reason, many terminals experience a delay between the time a user presses
the escape key and the time the escape is returned to the program.

The
unget_wch
function pushes the wide character
wch
back onto the head of the input queue, so the wide character
is returned by the next call to
get_wch. The pushback of
one character is guaranteed. If the program calls
unget_wch
too many times without an intervening call to
get_wch,
the operation may fail.

Function Keys

The following function keys, defined in
<curses.h>, may be returned by
get_wch
and related
functions if
keypad
has been enabled. Note that a particular
terminal may not support all of these function keys. In other words, the routines
do not return a function key if the terminal does not transmit a unique code
when the key is pressed or if the definition for the key is not present in
the
terminfo
database,

NOTES

The header file
<curses.h>
automatically
includes the header file
<stdio.h>.

Applications should not define the escape key by itself as a single-character
function.

When using
get_wch,
wget_wch,
mvget_wch, or
mvwget_wch, applications should
not use
nocbreak
mode and
echo
mode
at the same time. Depending on the state of the tty driver when each character
is typed, the program may produce undesirable results.

Note that
get_wch,
mvget_wch,
and
mvwget_wch
may be macros.

RETURN VALUES

When
get_wch,
wget_wch,
mvget_wch, and
mvwget_wch
functions successfully
report the pressing of a function key, they return
KEY_CODE_YES. When they successfully report a wide character, they return
OK. Otherwise, they return
ERR.